1. field of the Invention
This invention relates to a heat exchanger of the kind hereinafter referred to as being of the kind specified, in which fluid to be cooled is passed through finned tubes over which air flows, the air flow being assisted by a natural draught tower and/or by fan or other means for providing a forced or induced draught.
A heat exchanger of the kind specified also comprises a plurality of finned tubes, the tubes being grouped together into banks, each bank comprising a plurality of parallel, finned tubes arranged side by side, two such banks being associated with one another to form a frame, the banks being inclined to one another so that they diverge from an apex of the frame, the tubes of each bank being arranged with their longitudinal axes generally parallel to the apex of the frame.
The fluid to be cooled by the heat exchanger may change its state, i.e. be condensed, or may be cooled without change of state. Such heat exchangers find application in condensing steam and/or cooling condensate from steam turbines.
2. Description of the prior art
Heretofore each bank of tubes has comprised supporting frame members extending parallel to the tubes and connected at their ends to headers with which the ends of the tubes are also connected. The frame members adjacent the apex of the frame have been connected by a blanking plate. When a plurality of frames have been arranged side by side to form a heat-exchanger assembly, blanking plates have also been connected between the frame members of adjacent banks of adjacent frames. Where the frames have been arranged with the apices generally horizontal so that there are upper and lower supporting frame members of each bank, the lower frame members of adjacent banks have been connected by blanking plates as have the upper frame members of adjacent banks. Moreover, adjacent lower frame members have been supported on beams of a supporting framework extending parallel to and below the lower frame members. In this arrangement the frames are A-frames or V-frames with the banks diverging downwardly and upwardly respectively from the apex of the frame.
In such an assembly of A-frames or V-frames, which presents a zig-zag shape in vertical section, the inclined flanks of the shape contain the finned tubes over which the air flows but the upper and lower apices of the shape are formed by the upper and lower supporting frame members and blanking plates and therefore represent wasted parts of the plan area (i.e. horizontal projected area) of the heat-exchanger assembly since they provide no heat-exchange surface.
An object of one aspect of the invention is to provide a heat exchanger of the kind specified which has more usuable heat exchange surface than previously known heat exchangers of this kind.